Tallin vs Tallinn

Tallin and Tallinn both are nouns.

Word	Noun	Adjective	Verb	Adverb
Tallin	Yes	No	No	No
Tallinn	Yes	No	No	No

As nouns, Tallin and Tallinn are synonyms defined as:

Tallin and Tallinn: a port city on the Gulf of Finland that is the capital and largest city of Estonia

Other synonyms of Tallin include capital of Estonia.

Tallin (noun)	Tallinn (noun)
a port city on the Gulf of Finland that is the capital and largest city of Estonia	a port city on the Gulf of Finland that is the capital and largest city of Estonia